In my experience the leather ones run TTS and the patent leather run a little small. If you've never worn shoes with elastic in the heel they may take a little getting used to. When I first tried them on I tried my real size and 1/2 size up and debated for a while which I should keep. I found that the elastic pushed my foot forward and make them feel smaller. I ended up keeping my real size and after wearing them a time or two they're fine. HTH!
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“Ginger Rogers did everything Fred Astaire did. She just did it backwards and in high heels.” Ann W. Richards
TTS. Don't go bigger because the leather elastic in the back will bunch up and be annoying. But also be careful not to go too small or else your toes will be totally crushed.